OVS-FLOWVIZ(8) Open vSwitch OVS-FLOWVIZ(8)

ovs-flowviz - utility for visualizing OpenFlow and datapath flows

ovs-flowviz [-i [alias,]file | --input [alias,]file] [-c file | --config file] [-f filter | --filter filter] [-h filter | --highlight filter] [--style style] flow-type format [args…]

ovs-flowviz --help

ovs-flowviz helps visualize OpenFlow and datapath flow dumps in different formats in order to make them more easily understood.

ovs-flowviz reads flows from stdin or from a file specified by the --input option, filters them, highlights them, and finally outputs them in one of the predefined formats.

Print a brief help message to the console.

File to read flows from. If not provided, ovs-flowviz will read flows from stdin.

This option can be specified multiple times. The file path can prepended by an alias that will be shown in the output. For example: --input node1,/path/to/file1 --input node2,/path/to/file2


Style configuration file to use, overriding the default one. Styles defined in the style configuration file can be selected using the --style option.

For more details on the style configuration file, see the Style Configuration File section below.


Flow filter expression. Only those flows matching the expression will be shown (although some formats implement filtering differently, see the Datapath tree format section below).

The filtering syntax is detailed in Filtering Syntax.


Highlight the flows that match the provided filter expression.

The filtering syntax is detailed in Filtering Syntax.


Style. The selected style must be defined in the style configuration file.

openflow or datapath.

See the Supported formats section.

ovs-flowviz supports several visualization formats for both OpenFlow and datapath flows:

Flow Type Format Description
Both console Prints the flows in a configurable, colorful style in the console.
Both json Prints the flows in JSON format.
Both html Prints the flows in an HTML list.
OpenFlow cookie Prints the flows in the console sorted by cookie.
OpenFlow logic Prints the logical structure of flows in the console.
Datapath tree Prints the flows as a tree structure arranged by recirc_id and in_port.
Datapath graph Prints a graphviz graph of the flows arranged by recirc_id and in_port.

The console format works for both OpenFlow and datapath flow types, and prints flows in the terminal using the style determined by the --style option.

Arguments:

Color of the packet and byte counters to reflect their relative size. The color gradient goes through the following colors: blue (coldest, lowest), cyan, green, yellow, red (hottest, highest)

Note filtering is applied before the range is calculated.


The json format works for both OpenFlow and datapath flow types, and prints flows in JSON format. See the JSON Syntax section for more details.

The html format works for both OpenFlow and datapath flows, and prints flows in an HTML table that offers some basic interactivity. OpenFlow flows are sorted in tables and datapath flows are arranged in flow trees (see Datapath tree format for more details).

Styles defined via Style Configuration File and selected via --style option also apply to the html format.

The OpenFlow cookie format is similar to the console format but instead of arranging the flows by table, it arranges the flows by cookie.

The OpenFlow logic format helps visualize the logic structure of OpenFlow pipelines by arranging flows into logical blocks. A logical block is a set of flows that have:

  • Same priority.
  • Match on the same fields (regardless of the match value and mask).
  • Execute the same actions (regardless of the actions’ arguments, except for resubmit and output).
  • Optionally, the cookie can be included as part of the logical flow.

Arguments:

Show all the flows under each logical block.

Use ovn-detrace.py script to extract cookie information (implies ‘-c’).

Consider the cookie in the logical block.

Use an alternative path to search for ovn_detrace.py.

OVN NB database connection method (implies ‘-d’). Default: “unix:/var/run/ovn/ovnnb_db.sock”.

OVN SB database connection method (implies ‘-d’). Default: “unix:/var/run/ovn/ovnsb_db.sock”.

Specify the filter to be run on the ovn-detrace information. Syntax: python regular expression (See https://docs.python.org/3/library/re.html).

Change the color of the packet and byte counters to reflect their relative size. The color gradient goes through the following colors: blue (coldest, lowest), cyan, green, yellow, red (hottest, highest)

Note filtering is applied before the range is calculated.


The datapath tree format arranges datapath flows in a hierarchical tree. The tree is comprised of blocks with the same recirc_id and in_port. Within those blocks, flows with the same action are combined. And matches which are the same are omitted to reduce the visual noise.

When a flow’s actions includes the recirc() action with a specific recirc_id, flows matching on that recirc_id and the same in_port are listed below. This is done recursively for all actions.

The result is a hierarchical representation that shows how actions are related to each other via recirculation. Note that flows with a specific non-zero recirc_id are listed below each group of flows that have a corresponding recirc() action. Therefore, the output contains duplicated flows and can be verbose.

Filtering works in a slightly different way for datapath flow trees. Unlike other formats where a filter simply removes non-matching flows, the output of a filtered datapath flow tree will show full sub-trees that contain at least one flow that satisfies the filter.

The html format prints this same tree as an interactive HTML table and the graph format shows the same tree as a graphviz graph.

The datapath graph generates a graphviz visual representation of the same tree-like flow hierarchy that the tree format prints.

Arguments:

Print the graphviz format as an svg image alongside an interactive HTML table of flows.

Printing a single-file OpenFlow or datapath dump without PMD thread blocks in json format results in a list of JSON objects, each representing a flow.

This list can be found inside one or more levels of JSON dictionaries if multiple files are processed (filename used as key) or if PMD thread blocks are found in datapath flows (name of the thread used as key).

Each flow object includes the following keys:

Original flow string.
Object with the flow information such as: cookie, duration, table, n_packets, n_bytes, etc.
Object with the flow match. For each match, the object contains a key-value where the key is the name of the match as defined in ovs-fields(7) and ovs-ofctl(8), and the value represents the match value. The way each value is represented depends on its type. See Value representation.
List of action objects. Each action is represented by an JSON object that has one key and one value. The key corresponds to the action name. The value represents the arguments of the key. See Action representation.
The UFID (datapath flows only).

Values are represented differently depending on their type:

  • Flags: The value of flags is true.
  • Decimal / Hexadecimal: Represented by their integer value. If they support masking, represented by a dictionary with two keys: value contains the field value and mask contains the mask. Both are integers.
  • Ethernet: Represented by a string: {address}[/{mask}]
  • IPv4 / IPv6: Represented by a string {address}[/{mask}]
  • Registers: Represented by a dictionary with three keys: field` contains the field value (string), start, and end represent the first and last bit of the register value.

For example, the register

NXM_NX_REG10[0..15]


is represented as

{
    "field": "NXM_NX_REG10",
    "start": 0,
    "end": 15
},


Actions are generally represented by an object that has a single key and value. The key is the action name as defined ovs-actions(7).

The value of actions that have no arguments (such as drop) is (boolean) true.

The value of actions that have a list of arguments (e.g: resubmit([port],[table],[ct])) is an object that has the name of the argument as key. The argument names for each action is defined in ovs-actions. For example, the action

resubmit(,10)


is represented as

{
    "resubmit": {
        "port": "",
        "table": 10
    }
}


The value of actions that have a key-word list as arguments (e.g: ct([argument])) is an object whose keys correspond to the keys defined in ovs-actions(7). The way values are represented depends on the type of the argument. For example, the action

ct(table=14,zone=NXM_NX_REG12[0..15],nat)


is represented as

{
    "ct": {
        "table": 14,
        "zone": {
            "field": "NXM_NX_REG12",
            "start": 0,
            "end": 15
        },
        "nat": true
    }
}


The style configuration file is selected via the --config option and has INI syntax. It can define any number of styles to be used by both console and html formats. Once defined in the configuration file, formats are selected using the --style option.

INI sections are used to define styles, [styles.mystyle] defines a style called mystle. Within a section styles can be defined as:

[FORMAT].[PORTION].[SELECTOR].[ELEMENT] = [VALUE]


Either console or html
Part of the key-value the style applies to: key to indicate the key part of a key-value, value to indicate the value part of a key-value, flag to indicate a single flag or delim to indicate delimiters such as parentheses, brackets, etc.
Select the key-value the style applies to: highlighted to indicate highlighted key-values, type.<type> to indicate certain types such as IPAddress or EthMask or <keyname> to select a particular key name.
Select the style element to modify: color or underline (only for console format).
Ether a color hex, other color names defined in the rich python library (https://rich.readthedocs.io/en/stable/appendix/colors.html) or true if the element is underline.

A default configuration file is shipped with ovs-flowviz and its path is printed in the --help output. A detailed description of the syntax alongside some examples are available there.

ovs-flowviz provides rich highlighting and filtering. The special command ovs-flowviz filter dumps the filtering syntax:

$ ovs-flowviz filter
Filter Syntax
*************
   [! | not ] {key}[[.subkey]...] [OPERATOR] {value})] [LOGICAL OPERATOR] ...
  Comparison operators:
      =   equality
      <   less than
      >   more than
      ~=  masking (valid for IP and Ethernet fields)
  Logical operators:
      !{expr}:  NOT
      {expr} && {expr}: AND
      {expr} || {expr}: OR
  Matches and flow metadata:
      To compare against a match or info field, use the field directly, e.g:
          priority=100
          n_bytes>10
      Use simple keywords for flags:
          tcp and ip_src=192.168.1.1
  Actions:
      Actions values might be dictionaries, use subkeys to access individual
      values, e.g:
          output.port=3
      Use simple keywords for flags
          drop
  Examples of valid filters:
      nw_addr~=192.168.1.1 && (tcp_dst=80 || tcp_dst=443)
      arp=true && !arp_tsa=192.168.1.1
      n_bytes>0 && drop=true


Example expressions:

n_bytes > 0 and drop
nw_src~=192.168.1.1 or arp.tsa=192.168.1.1
! tcp && output.port=2


Print OpenFlow flows sorted by cookie adding OVN data to each one:

$ ovs-flowviz -i flows.txt openflow cookie --ovn-detrace


Print OpenFlow logical structure, showing the flows and heat-map:

$ ovs-flowviz -i flows.txt openflow logic --show-flows --heat-map


Display OpenFlow flows in HTML format with “light” style and highlight drops:

$ ovs-flowviz -i flows.txt --style "light" --highlight "n_packets > 0 and drop" openflow html > flows.html


Display the datapath flows in an interactive graphviz + HTML view:

$ ovs-flowviz -i flows.txt datapath graph --html > flows.html


Display the datapath flow trees that lead to packets being sent to port 10:

$ ovs-flowviz -i flows.txt --filter "output.port=10" datapath tree


The Open vSwitch Development Community

2016-2024, The Open vSwitch Development Community

December 16, 2024 3.4.90